The present invention concerns replaceable ink supply containers for providing ink to a high flow rate ink delivery system, and more particularly to a pressurized ink container having a chassis that performs a number of functions.
High throughput printing systems, such as those used in high speed printers and color copiers, or large format devices put heavy demand on an ink delivery system. The printhead must operate at a very high frequency. At the same time, print quality expectations keep rising. In order to maintain high print quality, the printhead must be able to rapidly eject ink without causing large fluctuations in the printhead pressure level.
One approach to this is to provide a pressure regulator integral to the printhead. The regulator receives ink at a first pressure and delivers ink to the printhead at a controlled second pressure. In order for this control to work, the first pressure must always be greater than the second pressure. Because of dynamic pressure drops, very high pixel rate printing requires that the first pressure be at a positive gauge pressure.
One example of an ink cartridge that can be pressurized is described in U.S. Pat. No. 4,568,954. Other references include U.S. Pat. Nos. 4,558,326; 4,604,633; 4,714,937; 4,977,413; Saito U.S. Pat. Nos. 4,422,084; and 4,342,041.
One problem with previous high throughput devices is predicting when the consumable will be exhausted. It is important that the system stop printing when the ink cartridge is nearly empty, with a small amount of stranded ink. Otherwise, dry firing and consequent printhead damage may occur. Printheads for such high throughput devices tend to be expensive. What is needed is an ink cartridge that offers pressurized ink and provides an accurate means of indicating the low ink condition.
To provide an ink container having all of these features is a challenge. As can be appreciated, such an ink container can become very complicated, making manufacture very difficult and expensive. What is need is a way of simplifying the construction and of providing all these features with a relatively simple and manufacturable design.
A chassis is provided that offers multiple functionality for an ink container for an inkjet printing system. The chassis rigidly supports an air inlet for receiving pressurized air from the printing system and an ink outlet for delivering pressurized ink to the system. The chassis supports a collapsible ink container by providing an attach surface over which the collapsible container is attached. The attach surface allows a relatively simple pleated bag construction to be used by providing a surface whose normal is substantially perpendicular to the longitudinal axis of the container. The chassis is adapted to engage with a pressure vessel opening, providing a seal that separates the pressure vessel from an outside atmosphere. The chassis provides a surface for outside electrical contacts along with locating means for a mating electrical connector, and provides pathways for them to be routed into the pressure vessel region.
Thus, in accordance with an aspect of the invention, an ink container for holding a supply of liquid ink for use in an inkjet printing system is described, and includes a collapsible ink reservoir for holding a supply of liquid ink, and a chassis. The chassis includes a first tower structure extending from an external surface of the ink container, an attach surface for attachment of said ink reservoir to said chassis, an ink path extending through the chassis from the first tower structure and the ink reservoir, a second tower structure extending from the external surface, and an air passageway extending through the second tower structure.
A method for assembling an ink container to be installed in a printing system is also described, and comprises the steps of:
(a) providing a chassis including a leading surface, a trailing surface, the leading surface having a fluid outlet projection with a distal end, the trailing surface having a fluid inlet conduit, the distal end and the fluid inlet conduit are fluidically coupled;
(b) fluidically coupling a collapsible reservoir to said chassis;
(c) attaching a valve to said distal end of said fluid outlet projection, said valve is adapted to engage a needle to allow ink to flow from said valve to said needle when said ink container is installed in said printing system;
(d) providing a pressure vessel having an opening for receiving said collapsible reservoir, said chassis is adapted to engage and seal said opening;
(f) inserting said reservoir into said opening; and
(g) positioning said chassis to seal said opening.